N-Disubstituted carbamoyloxy flavones

ABSTRACT

The invention relates to new flavone derivaties which have at least one N-disubstituted carbamoyloxy unit (OOCNR 6 (R 7 ))coupled directly to one or both aromatic rings of the flavone molecule.

CROSS REFERENCE

[0001] This application relies on Provisional Application No. 60/234,239filed on Sep. 21, 2000 which is relied upon and incorporated byreference herein.

FIELD OF THE INVENTION

[0002] The invention relates to novel flavones and to processes ofmaking them.

BACKGROUND OF THE INVENTION

[0003] Flavonoids, such as flavones, are natural products produced byliving organisms. Many of these compounds are natural products that donot appear to have any obvious metabolic or evolutionary function andmay be formed by “metabolic accident” or are by-products of thesynthetic machinery of the cellular enzymes. Regardless of their utilityto the parent organism, their value to man as drugs, herbs, flavorings,poisons, dyes, and the like is undisputed.

[0004] The subject flavones comprise oxygenated derivatives of aromaticring structures. Derivatives of flavone are found throughout the plantkingdom and especially in the higher plants. Although many biologicallyactive flavone derivatives have been found in nature, they also havebeen produced synthetically. Certain of these compounds are useful asrespiratory stimulants (U.S. Pat. No. 3,147,258), as an inhibitor of MAPkinase (Mahboobi, S., Pongratz, H., Synthesis of2′-Amino-3′methoxyflavone (PD 98059), Synth. Commun., 1999;29:1645), andas an antitumor agent (Akama T., et a., Structure-activity relationshipsof the 7-substituents of 5,4′-diamino-6,8,3′trifluoroflavone, a potentantitumor agent, J. Med. Chem., Jun. 4, 1998;41(12):2056-67). Anacetylcholine esterase inhibitor compound was described in Rampa A., etal., Acetylcholinesterase inhibitors: synthesis and structure-activityrelationships of omega-[N-methyl-N-(3-alkylcarbamoyloxyphenyl) methyl]aminoalkoxyheteroaryl derivatives, J. Med. Chem., Oct. 8,1998;41(21):3976-86, in which the flavone structure has a phenyl groupbearing an N-methylcarbamoyloxy radical connected with the oxygen atomof the flavone skeleton via a five membered chain:

[0005] Flavonoids serve as antioxidants and chemoprotectants againstmolecular damage from reactive oxygen species (ROS). Their antioxidativeactivity has been the subject of many studies (e.g., van Acker SA, etal., Structural aspects of antioxidant activity of flavonoids, FreeRadic. Biol. Med., 1996;20(3):331-42).

[0006] Oxidative stress, manifested by, for example. protein oxidationand lipid peroxidation is one characteristic of the brain of a personsuffering from Alzheimer's Disease (AD) (Cf. Varadarajan S, et al.,Alzheimer's amyloid beta-peptide-associated free radical oxidativestress and neurotoxicity, J. Struct. Biol., 2000 June; 130(2-3):184-208.The beneficial effect of various antioxidants in the treatment of AD isnow widely recognized. Cf. Pratico D, Delanty N., Oxidative injury indiseases of the central nervous system: focus on Alzheimer's disease,Am. J. Med., 2000 November;109(7):577-85; Giacobini E., Present andfuture of Alzheimer therapy, J. Neural. Transm. Suppl., 2000;59:231-42;Aisen, PS., et al., Anti-inflammatory and antioxidant therapies inAlzheimer's disease, Funct. Neurobio. Aging, 487-492 (Hof and MobbsedS., Academic Press: San Diego, Calif. 2001). Various compoundsincorporating a carbamoyl functionality (e.g., rivastigmine andphysostigmine) are useful for the treatment of AD via enhancement ofcholinergic transmission through inhibition of acetylcholinesterase(AChE).

[0007] The compounds of the present invention were designed as potentialtherapeutic agents for the treatment of AD by combining both ACHEinhibitory activity and antioxidant activity (by virtue of theircarbamoyl and flavonoid pharmacophores).

SUMMARY OF THE INVENTION

[0008] The invention relates to compounds of the general Formula I:

[0009] wherein each of R¹, R², R³, R⁴ and R⁵ is a substituent selectedfrom the group consisting of:

[0010] hydrogen;

[0011] OOCNR⁶(R⁷), in which each of R⁶ and R⁷ is hydrogen, or a loweralkyl (C₁-C₄) and in which each of R⁶ and R⁷may be the same ordifferent;

[0012] OR⁸, wherein R⁸ is hydrogen or a lower alkyl (C₁-C₄);

[0013] wherein each of R⁹ and R¹⁰ is hydrogen or a lower alkyl (C₁-C₄);

[0014] a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide;

[0015] COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or a loweralkyl (C₁-C₄);

[0016] CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen or a loweralkyl (C₁-C₄);

[0017] NO₂; and

[0018] CN; and

[0019] wherein at least one of R¹, R², R³, R⁴ and R⁵ is OOCNR⁶(R⁷).

DETAILED DESCRIPTION OF THE INVENTION

[0020] The invention relates to new flavone derivatives of Formula Iabove which have at least one N-disubstituted carbamoyloxy unit(OOCNR⁶(R⁷)) coupled directly to one or both aromatic rings of theflavone molecule. Accordingly, the invention embraces compounds ofFormulae IA, IB and IC, below. Compounds of Formula IA are characterizedby the formula:

[0021] wherein R⁴ is OOCNR⁶(R⁷), in which each of R⁶ and R⁷ is hydrogenor a lower alkyl of 1 to 4 carbon atoms and in which each of R⁶ andR⁷may be the same or different, and wherein R⁴ occurs in the 2, 3 or 4position; and

[0022] wherein each of R¹, R², R³, and R⁵ is a substituent selected fromthe group consisting of:

[0023] hydrogen;

[0024] OR⁸, wherein R⁸ is hydrogen or a lower alkyl of 1 to 4 carbonatoms,

[0025] wherein each of R⁹ and R¹⁰ is hydrogen or a lower alkyl (C₁-C₄);

[0026] a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide;

[0027] COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or a loweralkyl (C₁-C₄);

[0028] CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen or a loweralkyl (C₁-C₄);

[0029] NO₂; and

[0030] CN.

[0031] Compounds of Formula IB are characterized by the followingformula:

[0032] wherein R¹ is OOCNR⁶(R⁷), in which each of R⁶ and R⁷ is hydrogenor a lower alkyl (C₁-C₄) and in which each of R⁶ and R⁷may be the sameor different, and wherein R¹ occurs in the 5, 6, 7, or 8 position; and

[0033] wherein each of R², R³, R⁴ and R⁵ is a substituent selected fromthe group consisting of:

[0034] hydrogen;

[0035] OR⁸, wherein R⁸ is hydrogen or a lower alkyl (C₁-C₄);

[0036] wherein each of R⁹and R¹⁰ is hydrogen or a lower alkyl (C₁-C₄);

[0037] a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide;

[0038] COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or a loweralkyl (C₁-C₄);

[0039] CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen or a loweralkyl (C₁-C₄);

[0040] NO₂; and

[0041] CN.

[0042] The compounds of Formula IC are characterized by the followingformula:

[0043] wherein each of R¹ and R⁴ is OOCNR⁶(R⁷ ) and R¹ occurs in the 5,6, 7, or 8 position and R⁴ occurs in the 2, 3, or 4 position, and eachof R⁶ and R⁷ is hydrogen or a lower alkyl (C₁-C₄) and in which each ofR⁶ and R⁷may be the same or different; and

[0044] wherein each of R², R³, and R⁵ is a substituent selected from thegroup consisting of:

[0045] hydrogen;

[0046] OR⁸, wherein R⁸ is hydrogen or a lower alkyl (C₁-C₄);

[0047] wherein each of R⁹ and R¹⁰ is hydrogen or a lower alkyl (C₁-C₄);

[0048] a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide;

[0049] COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or a loweralkyl (C₁-C₄);

[0050] CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen or a loweralkyl (C₁-C₄);

[0051] NO₂; and

[0052] CN.

[0053] The definitions of each of R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³indicates that each may be an alkyl of 1 to 4 carbon atoms, for example,methyl, ethyl, isopropyl, butyl, isobutyl or t-butyl.

[0054] Compounds of the invention are prepared by reacting ahydroxyflavone reactant with dialkylcarbamoyl chloride (R⁶R⁷NCOCl) inthe presence of a base such as sodium hydride or potassium carbonate,according to the following reaction scheme:

[0055] The reaction is carried out in an organic solvent such asdimethylformamide, acetonitrile or in a mixture of dimethylformamide andacetonitrile. The reaction can be undertaken at room temperature or upto about the boiling or reflux temperature of the solvent. For example,when the solvent contains acetonitrile, the reaction can be carried outat up to about 82° C., as determined by the boiling point ofacetonitrile.

[0056] The hydroxyflavone reactant, used for production of the inventioncompounds in the reaction scheme set forth above, can be prepared bymany methods. Various methods of hydroxyflavone synthesis are describedin “The Chemistry of Flavonoid Compounds,” Geissman, ed., Perg. Press(1962), which is relied upon and incorporated by reference herein.According to the synthetic method, shown below, the starting material isan appropriately substituted 2-hydroxyacetophenone derivative. The2-hydroxyacetophenone derivative is the precursor for production of aphenolester derivative. In turn, the phenolester derivative issynthesized by reacting an aromatic acid chloride with the2-hydroxyacetophenone derivative in a manner described, for example, inOrg. Synth. Coll., vol. IV, 478 (1963), which is relied upon andincorporated by reference herein. That phenolester is treated withalkali hydroxide(s) in pyridine to effect a Baker-Venkataramanrearrangement to produce a 1, 3-diketone, as described in J. Chem. Soc.,1381 (1933) and in Curr. Sci., 4, 214 (1933), each of which is reliedupon and incorporated by reference herein.

[0057] Ring closure of the 1,3-diketone, in the presence of mineral acidin acetic acid as a solvent, results in a flavone derivative having atleast one alkoxy group. This compound is subjected to a dealkylationresulting in the desired hydroxyflavone compound as a precursor for thesynthesis of new dialkylaminocarbamoyloxy derivatives of flavones.

[0058] Specific embodiments of the invention include compounds ofFormula II:

[0059] wherein R¹, R², R³ and R⁴ are selected from the group consistingof:

[0060] hydrogen;

[0061] OOCNR⁵(R⁶), wherein each of R⁵ and R⁶ is a lower alkyl (C₁-C₄)and in which each of R⁵ and R⁶ may be the same or different;

[0062] OR⁷, wherein R⁷ is a lower alkyl (C₁-C₄);

[0063] wherein each of R⁸ and R⁹ is hydrogen or a lower alkyl (C₁-C₄);

[0064] a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide;

[0065] COOR¹⁰, wherein R¹⁰ is hydrogen, sodium, potassium, or a loweralkyl (C₁-C₄);

[0066] CONR¹¹R¹², wherein each of R¹¹ and R¹² is hydrogen, or a loweralkyl (C₁-C₄);

[0067] NO₂; and

[0068] CN; and

[0069] wherein at least one of R¹, R², R³ and R⁴ is OOCNR⁵(R⁶).

[0070] Specific compounds of Formula II are set forth in Table I: TABLEI Example R¹ R² R³ R⁴ 1 H H Me₂NCOO H 2 H H Et, MeNCOO H 3 H H H Me₂NCOO4 H H H Et, MeNCOO 5 H OEt Me₂NCOO H 6 H OEt Et, MeNCOO H 7 H Me₂NCOOOme H 8 H Me₂NCOO Me₂NCOO H 9 NH₂ H H Me₂NCOO 10  NMe₂ H H Me₂NCOO

[0071] In the table, Me is methyl and Et is ethyl.

[0072] Compounds of Examples 1 and 2 below were prepared by thefollowing synthetic route:

[0073] Compounds of Examples 5, 6, 7 and 8 below were prepared by thefollowing synthetic route:

[0074] Compounds of Examples 9 and 10 below were prepared by thefollowing synthetic route:

[0075] Compounds of the invention were tested for acetylcholine esteraseinhibition and did exhibit acetylcholine esterase inhibition. By way ofbackground, acetylcholine may either increase muscle contraction (frogskeletal muscle) or decrease it (frog cardiac muscle) depending on theidentity of the choline receptor affected and treated (MolecularBiology, Scientific American Books (Third Edition), p. 957 (1997)).During hydrolysis of acetylcholine by acetylcholine esterase, the acetylgroup reacts with serine to produce toxins and inhibitors. Such toxinsprolong the action of acetylcholine, prolonging the period of membranedepolarization. Such inhibitors can be lethal if they prevent relaxationof the muscles necessary for breathing (Id. at 965).

[0076] As pharmaceutical reagents, the carbamoyl derivatives of flavonesof the invention can be compounded or diluted with pharmaceuticallyacceptable carriers and diluents, both liquid and solid, and formed intocapsules or tablets for oral administration or formulated as solutionsfor parenteral administration, by intravenous or intramuscularadministration. The invention also embraces inhibiting acetylcholineesterase activity by administering a compound of Formula I to amammalian host in need of acetylcholine esterase inhibition.

[0077] The results of the acetylcholine esterase inhibitory activitytesting are set forth in Table II: TABLE II AChE Activity of FlavoneDerivatives AchE inhibition structure IC₅₀(μM) Ex vivo

2.65 29% at 40 μM/kg

1.4 42% at 40 μM/kg

41

3.5 14% at 50 μM/kg

10.5 (5′) 48 (30′)

5.5 (5′) 6 (30′)

10 (5′) No inhibition at >50 Mmol/kg 5.8 (30′)

[0078] The foregoing ex vivo results recommend application oftherapeutically effective amounts of composition of the invention tomammalian hosts, including human hosts, to inhibit acetylcholineesterase activity, and diseases associated with such activity, forexample, AD. The following examples are illustrative of the invention.However, the examples simply present specific embodiments of theinvention. The invention embraces the subject matter of the appendedclaims and all equivalents thereof.

EXAMPLES Example 1 2′ (N,N-Dimethylcarbamoyloxy) flavone Example 1a2-Methoxybenzoyl chloride

[0079] A mixture of 2-methoxybenzoic acid (45.6 g, 0.3 mol), thionylchloride (53.5 g, 33 ml, 0.45 mol) and dimethylformamide (two drops) wasrefluxed for an hour. Excess thionyl chloride was then distilled offunder reduced pressure. Benzene (50 ml) was added to the residue and thesolvent was distilled off until the weight of the residue remainedunchanged (about 51 g).

Example 1b 2-[(2-Methoxybenzoyl)oxy]-acetophenone

[0080] 2-Methoxybenzoyl chloride (about 51 g) from Example 1a was addeddropwise to a mixture of 2-hydroxyacetophenone (27.2 g, 24.1 ml, 0.20mol) and pyridine (40 ml). The reaction mixture was warmed to about 60°C. exothermically. After stirring for 15 minutes, the reaction mixturewas poured onto a mixture of ice (800 g) and 36% hydrochloric acid (120ml). The solid was filtered off, washed with water, and dried. The crudeproduct was crystallized from methanol to yield 48.4 g (89.6%) of thecompound (m.p.: 78-79° C.).

Example 1c 1-(2-Hydroxyphenyl)-3-(2-methoxyphenyl)-propan-1,3-dione

[0081] 2-[(3-Methoxybenzoyl)oxy]-acetophenone (40.5 g, 0.15 mol) inpyridine (135 ml) was warmed to 50° C., and pulverized potassiumhydroxide (12.6 g, 0.225 mol) was added to the solution gradually. Thetemperature of the reaction mixture rose spontaneously to 70-80° C. Themixture was mechanically stirred for 15 minutes, during which time acopious precipitate formed. The mixture was cooled to room temperatureand acidified with 10% acetic acid (200 ml). The product was collectedon a filter and washed with water and methanol. The yield was 29.3 g(72.3%) (m.p.: 80-84° C.).

Example 1d 2′-Methoxyflavone

[0082] A solution of1-(2-hydroxyphenyl)-3-(2-methoxyphenyl)-propan-1,3-dione (27 g, 0.1 mol)in acetic acid (130 ml) and concentrated sulfuric acid (5 ml) wereplaced in a flask fitted with a reflux condenser and a stirrer. Theflask was heated in a bath maintained at 100° C. for an hour. Then thereaction mixture was poured onto crushed ice (750 g). The solid wasfiltered off, washed with water, dried and crystallized from methanol togive 24.3 g (96.2 %) of the compound (m.p.: 97-98.5° C.). In theliterature (J. Org. Chem., 27, 381 (1962)), 102-103° C. is given for theproduct melting point.

Example 1e 2′-Hydroxyflavone from 2′-methoxy-flavone

[0083] A mixture of 2′-methoxyflavone (12.6 g, 0.05 mol), 33% hydrogenbromide in acetic acid (80 ml) and 47% hydrogen bromide in water (115ml) was refluxed for 8 hours; then the mixture was left to cool to roomtemperature. The solid was isolated by filtration and washed with aceticacid, water and acetone to afford 11.0 g (92.3 %) of the compound (m.p.:248-249° C.). The literature (J. Org. Chem., 1962, 27, 381 (1962))reports the product melting point as 246-247° C.

Example 1f 2′-Hydroxyflavonefrom1-(2-hydroxyphenyl)-3-(2-methoxyphenyl)-propan-1,3-dione

[0084] 1,3-Diketone (13.5 g, 0.05 mol) from Example 1c was used insteadof 2′-methoxy-flavone and the compound was prepared according to theprocedure described in Example 1e. The yield was 10.6 g (89.2 %) (m.p.:248-249° C.).

Example 1g 2′-(N,N-dimethylcarbamoyloxy)flavone

[0085] 2′-Hydroxyflavone (2.38 g, 0.01 mol) was dissolved indimethylformamide (100 ml), and 55-60% sodium hydride in mineral oil(0.48 g) was added to the solution. The reaction mixture was stirred atroom temperature for an hour. N,N-dimethylcarbamoyl chloride (1.29 g,1.10 ml, 0.012 mol) in dimethylformamide (5 ml) was added to thereaction mixture dropwise. The reaction mixture was stirred at roomtemperature for an hour. The inorganic salt was filtered off; and thefiltrate was evaporated to dryness under reduced pressure. During theevaporation, the bath temperature was not allowed to exceed 65° C. Theresidue was dissolved in warm diethyl ether and treated with charcoaland aluminium oxide. The solution was evaporated to a small volume. Thewhite crystals were collected by filtration, washed with petroleum ether(boiling range 40-60° C.) to afford 1.79 g (57.8%) of the compound(m.p.: 86.5-87.5° C.).

[0086] Analysis: calculated for C₁₈H₁₅NO₄: C, 69.89; H, 4.89; N, 4.53.

[0087] Found: C, 69.89; H, 4.73; N, 4.58.

[0088] IR (KBr): 1723, 1646 cm⁻¹ (CO).

[0089]¹H NMR (CDC1₃): δ=2.97 (s, 3H), 3.09 (s, 3H), 6.69 (s, 1H),7.2-8.3 (m, 8H).

Example 2 2′-(N-Ethyl-N-methylcarbamoyloxy)flavone

[0090] The crude compound was obtained, following the general procedureof Example 1g, from the reaction of 2′-hydroxyflavone (2.38 g, 0.01mol), N-ethyl-N-methylcarbamoyloxy chloride (1.46 g, 0.12 mol) andsodium hydride. The crude product was purified by column chromatography(silica, 7:1 CH₂Cl₂/EtOAc as eluent) and crystallized fromacetone-water. The yield was 1.52 g (47.0%) (m.p.: 68-70° C.).

[0091] Analysis: calculated for C₁₉H₁₇NO₄: C, 70.58; H, 5.30; N, 4.33.

[0092] Found: C, 70.45; H, 5.32; N, 4.29.

[0093] IR (KBr): 1712, 1640 cm⁻¹ (CO).

[0094]¹H NMR (CDCI₃): δ=1.14 (dt, 3H), 3.00 (ds, 3H), 3.41 (dq, 2H),6.67 (s, 1H), 7.2-8.3 (m, 8H).

Example 3 3′-(N,N-Dimethylcarbamoyloxy)flavone

[0095] 2.38 g (0.01 mol) of 3′-hydroxyflavone (m.p.: 209-211 ° C.)prepared from 3-methoxybenzoic acid and 2-hydroxyacetophenone (accordingto Examples 1a, b, c, f)) and potassium carbonate (2.21 g, 0.016 mol),was stirred in a combined solvent of dimethylformamide (50 ml) andacetonitrile (20 ml). N,N-Dimethylcarbamoyl chloride (1.18 g, 1.0 ml,0.11 mol) in acetonitrile (10 ml) was added to the reaction mixture overa period of 20 minutes. The reaction mixture was boiled under a refluxcondenser for 3 hours then poured onto crushed ice (400 g) andneutralized with hydrochloric acid. The product was filtered off andwashed with water to afford 2.89 g (93.4%) (m.p.: 125-126° C.).

[0096] Analysis: calculated for C₁₈H₁₅NO₄: C, 69.89; H, 4.89; N, 4.53.

[0097] Found: C, 69.76; H, 4.71; N, 4.41.

[0098] IR (KBr): 1718, 1654 cm⁻¹ (CO).

[0099]¹H NMR (CDCl₃): δ=3.07 (s, 3H), 3.17 (s, 3H), 6.83 (s, 1H),7.2-8.3 (m, 8H).

Example 4 3′-(N-Ethyl-N-methylearbamoyloxy)flavone

[0100] Starting from 3′-hydroxyflavone (2.38 g, 0.01 mol),N-ethyl-N-methylcarbamoyl chloride (1.46 g, 0.012 mol) and 55-60% sodiumhydride in mineral oil (0.48 g), the compound was synthesized utilizingthe procedure of Example 1g to give 2.60 g (80.4%) (m.p.: 109-111° C.).

[0101] Analysis: calculated for C₁₉H₁₇NO₄: C, 70.58; H, 5.30; N, 4.33.

[0102] Found: C, 70.21; H, 5.03; N, 4.37.

[0103] IR (KBr): 1738, 1652 cm⁻¹ (CO).

[0104]¹H NMR (CDCl₃): δ=1.22 (dt, 3H), 3.09 (ds, 3H), 3.50 (dq, 2H),6.83 (s, 1H), 7.2-8.4 (m, 8H).

Example 5 7-Ethoxy-2′-(N,N-dimethylcarbamoyloxy)flavone Example 5a7-Ethoxy-2′-methoxyflavone

[0105] 2,4-Dihydroxyacetophenone was alkylated with bromoethane inacetone in the presence of potassium carbonate to obtain2-hydroxy-4-methoxyacetophenone. Using this compound and2-methoxy-benzoic acid as starting materials, the syntheses according toExamples 1a, b, c, and d yielded the compound (m.p.: 153-154.5° C.).

[0106] IR (KBr): 1623cm⁻¹ (CO).

[0107]¹H NMR (CDCI₃): δ=1.49 (t, 3H), 3.94 (s, 3H), 4.15 (q, 2H),6.8-8.2 (m, 8

Example 5b 7-Ethoxy-2′-hydroxyflavone

[0108] 7-Ethoxy-2′-methoxyflavone (7.4 g, 0.025 mol) was agitated indichloromethane (100 ml). Boron tribromide (9.4 g, 3.6 ml, 0.0375 mol)in dichloromethane (100 ml) was added dropwise for an hour. Theagitation was continued at room temperature for 24 hours. The reactionmixture was poured onto a mixture of crushed ice (100 g) and 36%hydrochloric acid (10 ml). After stirring the mixture for an hour, theprecipitate was filtered off. 2.15 g (29%) of unreacted7-ethoxy-2′-methoxyflavone was recovered. The filtrate was evaporatedunder reduced pressure to remove dichloromethane. From the aqueousresidue, crude 7-ethoxy-2′-hydroxyflavone was obtained by filtration.The crude product was dried, thoroughly pulverized and treated withboiling chloroform for half an hour. The undissolved product wascollected by filtration from the cooled mixture; and the crude7-ethoxy-2′-hydroxyflavone was crystallized from dimethylformamide togive 3.10 g (43.9%) (m.p.: 295-297° C.).

[0109] IR (KBr): 1624 cm⁻¹ (CO).

[0110]¹H NMR (DMSO): δ=1.40 (t, 3H), 4.20 (q, 2H), 6.9-8.1 (m, 8H),10.76 (s, 1H).

Example 5c 7-Ethoxy-2′-( N-dimethlylcarbamoyloxy) flavone

[0111] Using 7-ethoxy-2′-hydroxyflavone (2.82 g, 0.01 mol) as startingmaterial, the compound was obtained according to Example 1g. The crudeproduct was crystallized from methanol to give 1.25g (35.4%) (m.p.:166-168° C.).

[0112] Analysis: calculated for C₂₀H₁₉NO₅: C, 67.98; H, 5.42; N, 3.96

[0113] Found: C, 67.95; H, 5.29; N, 3.99.

[0114] IR (KBr): 1736, 1637 cm⁻¹ (CO).

[0115]¹H NMR (CDCl₃): δ=1.50 (t, 3H), 2.99 (s, 3H), 3.10 (s, 3H), 4.14(q, 2H), 6.67 (s, 1H), 6.8-8.2 (m, 7H).

Example 6 7-Ethoxy-2′-(N-ethyl-N-methylcarbamoyloxy) flavone

[0116] The experiment was conducted in a manner analogous to theprocedure of Example 1g. 7-Ethoxy-2′-hydroxyflavone (2.82 g, 0.01 mol)and N-ethyl-N-methylcarbamoyl chloride (1.46 g, 0.012 mol) were used asstarting materials. The crude title compound was crystallized frommethanol to afford 1.35 g (36.7%) (m.p.: 91-93.5° C.).

[0117] Analysis: calculated for C₂₁H₂₁NO₅: C, 68.65; H, 5.76; N, 3.81.

[0118] Found: C, 68.30; H, 5.71; N, 3.80.

[0119] IR (KBr): 1731, 1643 cm⁻¹ (CO).

[0120]¹H NMR (CDCl₃): δ=1.14 (q, 3H), 1.49 (t, 3H), 3.03 (s, 3H), 3.42(m, 2H), 4.13 (q, 2H), 6.5-8.3 (m, 8H).

Example 7 7-(N,N-Dimethylcarbamoyloxy)-2′-methoxyflavone Example 7a7-Hydroxy-2′-methoxyflavone

[0121] A mixture of 7-ethoxy-2′-methoxyflavone (8.89 g, 0.03 mol) andaluminum chloride (20 g, 0.15 mol) in dichloromethane (300 ml) wasstirred at room temperature for 16 hours. The reaction mixture waspoured onto a mixture of crushed ice (500 g) and 36% hydrochloric acid(50 ml). The precipitate formed was filtered off, washed with water,dried and the crude compound was crystallized from dimethylformamide toafford 6.0 g (74.6%) (m.p.: 260-264° C.).

[0122] IR (KBr): 1625 cm⁻¹ (CO).

[0123]¹H NMR (DMSO): δ=3.91 (s, 3H), 6.8 (s, 1H), 6.85-8.0 (m, 7H),10.83 (s, 1H).

Example 7b 7-(N,N-Dimethylcarbamoyloxy)-2′-methoxyflavone

[0124] Starting from 7-hydroxy-2′-methoxyflavone (2.68 g, 0.01 mol), thecompound was prepared using a procedure analogous to that of Example 1g.The crude product was crystallized from methanol to give 1.36 g (40.1%)(m.p.: 133.5-135° C.).

[0125] Analysis: calculated for C₁₉H₁₇NO₅: C, 67.25; H, 5.05; N, 4.13.

[0126] Found: C, 66.86; H, 4.90; N, 4.08.

[0127] IR (KBr): 1728, 1642 cm⁻¹ (CO).

[0128]¹H NMR (DMSO); δ=2.97 (s, 3H), 3.10 (s, 3H), 3.94 (s, 3H), 6.94(s, 1H), 7.0-8.2 (m, 7H).

Example 8 7,2′-Di(N,N-dimethylcarbamoxyloxy)flavone Example 8a7,2′-Dihydroxyflavone

[0129] 7-Ethoxy-2′-methoxyflavone (7.4 g, 0.025 mol) and borontribromide (12.5 g, 4.4 ml, 0.05 mol) were added to dichloromethane (50ml). The reaction mixture was refluxed for two hours and then cooled toroom temperature. The solid was collected by filtration and washed withdichloromethane. The crude product was agitated in a mixture of coldwater (100 ml) and 36% hydrochloric acid (10 ml) for half an hour. Afterfiltration and washing with water, the wet product was dried andcrystallized from dimethylformamide to afford 5.63 g (88.6%) (m.p.:335-339° C.).

[0130] The literature (Berichte, 32, 1033(1899)) reports 320° C. as themelting point of this compound.

[0131] IR (KBr): 1618 cm⁻¹ (CO).

[0132]¹H NMR (DMSO); δ=6.80 (s, 1H), 6.85-8.0 (m, 7H), 10.67 (s, 1H),10.80 (s, 1H).

Example 8b 7,2′-Di(N, N-dimethylcarbamoyloxy)flavone

[0133] 7-2′-Dihydroxyflavone (5.09 g, 0.02 mol) and 55-60% sodiumhydride in mineral oil (1.92 g) were added into dimethylformamide (200ml). The mixture was stirred at room temperature for an hour.N,N-Dimethylcarbamoyl chloride (5.16 g, 4.4 ml, 0.048 mol) indimethylformamide (20 ml) was added dropwise for 15 minutes. Thereaction mixture was stirred at room temperature for 24 hours; then thesolvent was distilled off under reduced pressure. Ice-cold water (200 g)was added to the residue and the pH was adjusted to 7.0 with 17%hydrochloric acid. The crude product was filtered off, washed withwater, and crystallized from methanol and then acetone. The purecompound weighed 3.27 g (41.2%) (m.p.: 145.5-147° C.).

[0134] Analysis: calculated for C₂₁H₂₀N₂O₆: C, 63.63; H, 5.09; N, 7.07.

[0135] Found: C, 63.67; H, 5.05; N, 7.04.

[0136] IR (KBr): 1718, 1641 cm⁻¹ (CO).

[0137]¹H NMR (CDCl₃); δ=2.97 (s, 3H), 3.03 (s, 3H) 3.09 (s, 3H), 3.13(s, 3H), 6.69 (s, 1H), 7.1-8.3 (m, 7H).

Example 9 6-Amino-3′-(N,N-dimethylcarbamoyloxy)flavone Example 9a6-Amino-3′-hydroxyflavone

[0138] N-Acetyl-p-anisidine (m.p.: 127-130° C.) was obtained fromp-anisidine which was boiled in a mixture of acetic anhydride and aceticacid. 5-Acetamido-2-hydroxyacetophenone (m.p.: 165-167° C.) wassynthesized by Friedel-Crafts reaction from N-acetyl-p-anisidine (J.Chem. Soc., 3414 (1961)). Starting from 3-methoxy-benzoic acid and5-acetamido-2-hydroxyacetophenone, the compound,6-amino-3′hydroxyflavone, was synthesized according to Examples 1a, b,c, and f. The compound melted at 265-268° C.

[0139] IR (KBr): 1620 cm⁻¹ (CO).

[0140]¹H NMR (DMSO); δ=5.52 (s, 2H), 6.75 (s, 1H), 6.9-7.6 (m, 7H), 9.89(s, 1H).

Example 9b 6-Amino-3′-(N,N-dimethylcarbamoyloxy)flavone

[0141] The compound was produced from 6-amino-3′-hydroxyflavone (2.53 g,0.01 mol) according to the procedure of Example 3. The crude compoundwas purified by column chromatography (silica, 3: 1 EtOH/CHCl₃ aseluent) to yield 2.38 g (73.4%) (m.p.: 157-159° C.).

[0142] Analysis: calculated for C₁₈H₁₆N₂O₄: C, 66.66; H, 4.97; N, 8.64.

[0143] Found: C, 66.23; H, 4.87; N, 8.77.

[0144] IR (KBr): 1716, 1629 cm⁻¹ (CO).

[0145]¹H NMR (DMSO); δ=2.93 (s, 3H), 3.19 (s, 3H), 5.53 (s, 2H), 6.90(s, 1H), 6.95-8.0 (m, 7H).

Example 10 6-Dimethylamino-3′-(N,N-dimethylcarbamoyloxy)flavone Example10a 6-Amino-3′-methoxyflavone

[0146] 1-(2-Hydroxy-5-acetamidophenyl)-3-(3-methoxyphenyl)-propan-1,3-dione (98.2 g, 0.3 mol, m.p.: 72-73° C.) was synthesized from5-acetamido-2-hydroxyacetophenone and 3-methoxybenzoic acid according toExamples 1a, b, and c. It was then added to a combined solution ofacetic acid (300 ml) and 36% hydrochloric acid (150 ml). The reactionmixture was refluxed for 16 hours; then it was allowed to stand at roomtemperature for 16 hours. The product was isolated by filtration andwashed with methanol. The wet product was agitated in water (1000 ml),and the pH was adjusted to 11 with 25% ammonium hydroxide. The productwas filtered off and washed with water and ethanol to afford 75.4 g(94.0%) (m.p.: 203-206° C.).

[0147] IR (KBr): 1614 cm⁻¹ (CO).

[0148]¹H NMR (DMSO); δ=3.88 (s, 3H), 5.53 (s, 2H), 6.92 (s, 1H), 7.0-7.7(m, 7H).

Example 10b Trimethyl-6-(3′-methoxyflavonyl)ammonium iodide

[0149] A mixture of 6-amino-3′-methoxyflavone (53.5 g, 0.20 mol) andpotassium carbonate (96.7 g, 0.70 mol) in dimethylformamide (1250 ml)was stirred at room temperature for half an hour. Iodomethane (99.4 g,44 ml, 0.70 mol) was added and the reaction mixture was agitated at thesame temperature for 8 days. The solid was filtered off, thoroughlywashed with water, and dried. The yield was 73.6 g (84.1 %) (m.p.:189-191° C.).

Example 10c 6-Dimethylamino-3′-methoxyflavone

[0150] Trimethyl-6-(3′-methoxyflavonyl)ammonium iodide (43.7 g., 0.10mol) in ethanol-amine (175 ml) was stirred at 70° C. for an hour. Thereaction mixture was evaporated to dryness under reduced pressure.Methanol (100 ml) was added to the residue; and the solid was collectedby filtration. The wet crude product was boiled in chloroform (80 ml)for 10 minutes; and the solid was filtered off from the hot suspension.Methanol (170 ml) was added to the filtrate; and the solution wasconcentrated to 100 ml under reduced pressure by distillation. Afterstanding for 16 hours, the compound was collected by filtration andwashed with methanol to give 12.4 g (42.0%) (m.p.: 169-170.5° C.).

[0151] IR (KBr): 1618 cm⁻¹ (CO).

[0152]¹H NMR (CDCl₃); δ=3.06 (s, 6H), 3.39 (s, 3H), 6.80 (s, 1H),6.9-7.6 (m, 7H).

Example 10d 6-Dimethylamino-3-hydroxyflavone

[0153] 6-Dimethylamino-3′-methoxyflavone (11.8 g, 0.04 mol) was added toa mixture of 33% hydrobromic acid in acetic acid (40 ml) and 47%hydrobromic acid in water (80 ml). The reaction mixture was refluxed foran hour and then cooled to 10° C. The crystals were filtered off andwashed with water and ethanol. The crude compound was crystallized froma mixture of dimethylformamide and methanol to afford 9.35 g (83.2%)(m.p.: 233-235° C.).

[0154] IR (KBr): 1617 cm⁻¹ (CO).

[0155]¹H NMR (DMSO); δ=3.01 (s, 6H), 6.84 (s, 1H), 6.9-7.7 (m, 7H), 9.87(s, 1H).

Example 10e 6-Dimethylamino-3′-(N,N-dimethylcarbamoyloxy)flavone

[0156] Using 6-dimethylamino-3′-hydroxyflavone as starting material(2.81 g, 0.01 mol), the reaction was conducted in a manner analogous tothe process of Example 3. The crude title compound was crystallized froma mixture of chloroform and methanol to give 2.18 g (61.9%) (m.p.:167-168° C.).

[0157] Analysis: calculated for C₂₀H₂₀N₂O₄: C, 68.17; H, 5.72; N, 7.95.

[0158] Found: C, 68.12; H, 5.65; N, 8.08.

[0159] IR (KBr): 1727, 1637 cm⁻¹ (CO).

[0160]¹H NMR (CDCl₃); δ=3.03 (s, 9H), 3.14 (s, 3H), 6.80 (s, 1H),7.1-7.9 (m, 7H).

What is claimed is:
 1. A compound of the formula

wherein each of R¹, R², R³, R⁴ and R⁵ is a substituent selected from thegroup consisting of: hydrogen; OOCNR⁶(R⁷), in which each of R⁶ and R⁷ ishydrogen, methyl or ethyl and in which each of R⁶ and R⁷may be the sameor different; OR⁸, wherein R⁸ is hydrogen, methyl or ethyl

wherein each of R⁹ and R¹⁰ is hydrogen or methyl; a halogen atomselected from the group consisting of fluoride, chloride and iodide;COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or an alkyl of oneto two carbon atoms; CONR¹² R¹³, wherein each of R¹² and R¹³ ishydrogen, methyl or ethyl; NO₂; and CN; and wherein at least one of R¹,R², R³, R4 and R⁵ is OOCNR⁶(R⁷).
 2. A compound of the formula

wherein R⁴ is OOCNR⁶(R⁷ ), in which each of R⁶ and R⁷ is hydrogen,methyl or ethyl and in which each of R⁶ and R⁷may be the same ordifferent, and wherein R⁴ occurs in the 2, 3 or 4 position; and whereineach of R¹, R², R³, and R⁵ is a substituent selected from the groupconsisting of: hydrogen; OR⁸, wherein R⁸ is hydrogen, methyl, or ethyl;

wherein each of R⁹ and R¹⁰ is hydrogen or methyl; a halogen atomselected from the group consisting of fluoride, chloride, and iodide;COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or an alkyl of oneto two carbon atoms; CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen,methyl, or ethyl; NO₂; and CN.
 3. A compound of the formula

wherein R¹ is OOCNR⁶(R⁷), in which each of R⁶ and R⁷ is hydrogen, methylor ethyl and in which each of R⁶ and R⁷may be the same or different; andwherein R¹ occurs in the 5, 6, 7, or 8 position; and wherein each of R²,R³, R⁴ and R⁵ is a substituent selected from the group consisting of:hydrogen; OR⁸, wherein R⁸ is hydrogen, methyl, or ethyl;

wherein each of R⁹ and R¹⁰ is hydrogen or methyl; a halogen atomselected from the group consisting of fluoride, chloride, and iodide;COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or an alkyl of oneto two carbon atoms; CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen,methyl, or ethyl; NO₂; and CN.
 4. A compound of the formula

wherein each of R¹ and R⁴ is OOCNR⁶(R⁷ ) and R¹ occurs in the 5, 6, 7,or 8 position and R⁴ occurs in the 2, 3, or 4 position, and each of R⁶and R⁷ is hydrogen, methyl or ethyl and in which each of R⁶ and R⁷may bethe same or different; and wherein each of R², R³, and R⁵ is asubstituent selected from the group consisting of: hydrogen; OR⁸,wherein R⁸ is hydrogen, methyl, or ethyl;

wherein each of R⁹ and R¹⁰ is hydrogen or methyl; a halogen atomselected from the group consisting of fluoride, chloride, and iodide;COOR¹¹, wherein R¹¹ is hydrogen, sodium, potassium, or an alkyl of oneto two carbon atoms; CONR¹²R¹³, wherein each of R¹² and R¹³ is hydrogen,methyl, or ethyl; NO₂; and CN.
 5. A compound of the formula

wherein R¹, R², R³ and R⁴ are selected from the group consisting of:hydrogen; OOCNR⁵(R⁶), wherein each of R⁵ and R⁶ is methyl or ethyl andin which each of R⁵ and R⁶ may be the same or different; OR⁷, wherein R⁷is methyl or ethyl;

wherein each of R⁸ and R⁹ is hydrogen or methyl; a halogen atom selectedfrom the group consisting of fluoride, chloride, and iodide; COOR¹⁰,wherein R¹⁰ is hydrogen, sodium, potassium, or an alkyl of one to twocarbon atoms; CONR¹¹R¹², wherein each of R¹¹ and R¹² is hydrogen,methyl, or ethyl; NO₂; and CN; and wherein at least one of R¹, R², R³and R⁴ is OOCNR⁵(R⁶).
 6. A compound of the formula

wherein each of R¹, R², R³, R⁴ and R⁵ is a substituent selected from thegroup consisting of: hydrogen; OOCNR⁶(R⁷), in which each of R⁶ and R⁷ ishydrogen, or a lower alkyl of 1 to 4 carbon atoms and in which each ofR⁶ and R⁷may be the same or different; OR⁸, wherein R⁸ is hydrogen, or alower alkyl of 1 to 4 carbon atoms;

wherein each of R⁹ and R¹⁰ is hydrogen or a lower alkyl of 1 to 4 carbonatoms; a halogen atom selected from the group consisting of fluoride,chloride, bromide and iodide; COOR¹¹, wherein R¹¹ is hydrogen, sodium,potassium, or a lower alkyl of 1 to 4 carbon atoms; CONR¹²R¹³, whereineach of R¹² and R¹³ is hydrogen or a lower alkyl of 1 to 4 carbon atoms;NO₂; and CN; and wherein at least one of R¹, R², R³, R⁴ and R⁵ isOOCNR⁶(R⁷).
 7. The compound of claim 6, wherein each of said a loweralkyl is methyl or ethyl.
 8. A pharmaceutical composition comprising thecompound of claim 1 and a pharmaceutically acceptable carrier for saidcompound.
 9. A pharmaceutical composition comprising the compound ofclaim 2 and a pharmaceutically acceptable carrier for said compound. 10.A pharmaceutical composition comprising the compound of claim 3 and apharmaceutically acceptable carrier for said compound.
 11. Apharmaceutical composition comprising the compound of claim 4 and apharmaceutically acceptable carrier for said compound.
 12. Apharmaceutical composition comprising the compound of claim 5 and apharmaceutically acceptable carrier for said compound.
 13. Apharmaceutical composition comprising the compound of claim 6 and apharmaceutically acceptable carrier for said compound.
 14. A method forinhibiting acetylcholine esterase activity by administering a compoundof claim 1 to a host in need of acetylcholine esterase inhibition.
 15. Amethod for inhibiting acetylcholine esterase activity by administering acompound of claim 5 to a host in need of acetylcholine esteraseinhibition.
 16. A method for inhibiting acetylcholine esterase activityby administering a compound of claim 6 to a host in need ofacetylcholine esterase inhibition.